1. Field of the Invention
The present invention relates to a transverse gradient coil of a gradient coil assembly for a magnetic resonance imaging (MRI) system, and a method of manufacturing the transverse gradient coil.
2. Description of the Related Art
In known MRI systems, gradient coils are used to vary the strength of the magnetic field in particular locations of an imaging volume by introducing a constant gradient in a primary magnetic field. In this manner, particular regions of a sample may be selected for analysis.
In an effort to achieve significantly higher performance in MRI systems, the level of the current applied to the coils recently has been substantially raised. However, the increased current level produces a significant amount of heat. This heat has to be carried away to prevent damages to the coils, to avoid unwanted changes in the magnetic field due to heating of magnet components and to prevent unacceptable heating to the patient and other subjects in the MRI system.
Conventional transverse gradient coils are typically made with copper sheet backed with epoxy-glass resin substrate, so as to achieve insulation and structural performance. However, the epoxy-glass resin substrate limits thermal conduction because of its low thermal conductivity, about 0.2 W/m·K, so that it disadvantageously blocks the heat to be conducted away from the copper sheet and then taken away by cooling fluid in the cooling tubes in the remainder part of the gradient coil assembly. A plurality of cooling tubes are required to be embedded in the gradient coil assembly but cooling efficiency is highly constrained by epoxy-glass resin substrate.
Although several conventional approaches are developed to improve the cooling efficiency of the gradient assembly, including improving the cooling design or improving the thermal conductivity of the thermal conductivity of the material around cooling tubes, none of the conventional approaches addresses to improvement in the thermal conductivity of the insulation layer within a transverse gradient coil.